Phone interview - do I send a follow up thank you card?

I have a phone interview this week for a position that I would literally kill to get. I know the people interviewing me well. Should I send thank you cards after the interview? Or wait for potentially an in-person interview?

You don't think it'd be awkward to drop in where you just had a phone interview? It's not 1954, send a thank you email. Maybe do the hand written note (mailed not hand delivered) after a real interview.

Always, always, always send a thank you. An email is probably sufficient following a phone interview. A face to face absolutely demands a hand written note! Do not be classless. If you neglected to send a thank you note to me, I wouldn't hire you.